Stop Engine Oil Pressure! Warning

[crystalworks]

Originally Posted by wpoll

Nope - this part is not for M57 (or M57N) 3.0d diesel engines - it's for the N62 (4.4 and 4.8) V8 engines (according to Real OEM).

Which doesn't mean to say that there isn't a similar part with a similar failure mode in the M57 (or M57N) diesel.

I'll see if I can track anything down...

^What he said. Sorry didn't see the engine you had requested info on and most of the low oil pressure threads are for the V8's.

[Doru]

Could be something as simple as some slightly corroded electrical connections. Once you unplugged/plugged back in the sensor a couple times, it scratched the connecting surface enough to have contact. I'm sure you checked the contacts, but maybe try some 2000 sandpaper. There were also some reports concerning BMW electrical connectors that wrecked havoc due to the pins opening up too much, and making poor connection (on certain MAF's it was reported, and another part I can't remember right now). What people did, either changed the connector cartridge (pulling pins out) or twisting slightly the blade end that stabs in.

[upallnight]

I would replace the oil pump relief spring if you diesel employ such a mechanism. On an old Opel that my brother had he was getting a low oil pressure idiot light when the engine got hot. Turns out the oil pressure relief spring wasn't able to maintain the pressure for the plunger to control the amount of oil in the system when the engine got hot.

[hpy540]

Can just the relay for fan be bad? How common is that? Very common on e39
. I believe my fan not working causin ac not to work.

[wpoll]

Originally Posted by hpy540

Can just the relay for fan be bad? How common is that? Very common on e39
. I believe my fan not working causin ac not to work.

Looking at the wiring diagrams, I can't see a relay anywhere in the fan circuit.

The fan has 12v on the motor control board (inside the hub) anytime the ignition is on and a pulse-width modulated signal from the DME controls the fan on/off and speed modes.

If the fan runs when the pressure switch is disconnected, as you have indicated in another post, then the issue you have isn't likely to be related to the fan or it's control systems.

[dougal]

Damn! So I replaced the air-con auxiliary fan with a brand new BMW one. It solves the AC problem but not the oil pressure warnings.

I also changed the oil to 10/40 instead of 5/30. Didn't solve it either. New oil filter again, new pressure sensor too.

[wpoll]

Dougal, it's just occurred to me that a wire shorted to ground in the loom connecting the oil pressure switch could cause what you are seeing. Most oil pressure switches connect to ground to register the low pressure. My BMW F650GS Dakar motorcycle has had a similar fault - but in that case it was a faulty oil pressure switch. More than once in fact! Have you checked the loom carefully in the engine back, paying particular attention to look for any damage, heated or crushed sections of wiring?